Princess Diana documentary director reveals why he feels 'much more sympathetic' to Princes William and Harry

The Oscar-nominated director behind the upcoming documentary The Princess says he feels "much more sympathetic" to Prince William and Prince Harry after viewing archive footage.

Ed Perkins spooled through "hundreds of hours" of archive footage of Princess Diana for the piece, which is made up entirely of only television news footage and other public records to retell her story.

The film also charts the public spotlight on Lady Diana Spencer ahead of her marriage to Prince Charles, featuring scenes from the couple's 1983 Australia tour right through to the intense scrutiny she faced after their bitter divorce.

READ MORE: Prince Harry and Meghan Markle to receive humanitarian award for Archewell Foundation's work

Perkins told Metro UK the format lends itself to keeping the story unbiased and not "trying to be pro-monarchy or anti-monarchy, pro-Diana or anti-Diana".

"Not seeing them as characters in a sitcom, which is perhaps how I and lots of people have seen them, but actually, as human beings," he noted.

READ MORE: New documentary to examine police investigations into death of Princess Diana and the conspiracy theories

"That's been a really interesting and enlightening experience and I do feel much more sympathetic towards that and obviously very sad and sorry specifically for William and Harry for the many difficult things that they had to sort of go through, some of which are shown in the story."

The film, which made its debut at the Sundance Film Festival in January, is being released to coincide with the 25th anniversary of Diana's death on August 31.

"I think Diana's life for many years became a kind of national sitcom sort of soap opera. One of the questions the film is offering up is like, we want the fairytale but at what cost and at whose expense?" Perkins said.

The Princess is described as "a visceral submersion into Diana's life in the constant and often intrusive glare of the media spotlight".

It will allow "viewers to experience the overwhelming adoration, but also intense scrutiny of Diana's every move and the constant judgment of her character".

The Princess is in selected cinemas across Australia now.